Wheel Lug pattern from 4.5” to 5.5”

[Socnarftrucks]

Rookie question probably: I have a 81 f100 6 cyl with three on the tree. I’d like to change the wheel lug pattern from 4.5 to 5.5 to get some wheel wagon wheels. How do I do that? TIA

[Gary Lewis]

That's not as easy as it sounds. First, if I remember correctly, you'll need to change the front spindles, brake rotors, and calipers. But I think Dave/Fuzzface2 did that so I'll tag him.

Second, you'll have to change the rear axle, or at least the axle shafts, as well as the brakes.

I think the easiest thing to do is to buy another truck, swap the parts, and then sell the parts truck.

[FuzzFace2]

That's not as easy as it sounds. First, if I remember correctly, you'll need to change the front spindles, brake rotors, and calipers. But I think Dave/Fuzzface2 did that so I'll tag him.

Second, you'll have to change the rear axle, or at least the axle shafts, as well as the brakes.

I think the easiest thing to do is to buy another truck, swap the parts, and then sell the parts truck.

I am at work on my phone so when I get home on my pc I will answer the questions.

Dave ----

[FuzzFace2]

I am at work on my phone so when I get home on my pc I will answer the questions.

Dave ----

Ok at home on the PC.

From what I found between the 2 81 F100 trucks I had, 1 of each size.

You can not swap the rotors & calipers as the spindles & backing plates are different.

And if you are thinking of swapping the spindles to your truck that will not work either as the kingpins are different sizes.

This was all found when I bolted in the 4.5 beams as the assy. was in good working order but I did not have 4.5 wheel to fit so I tried to swap the rotors from the 5.5 to the 4.5 spindles and found no go

I had to rebuild my 5.5 assy.

So the easy way is to get the beams all the way out to the wheels.

Basic unbolt the beams and bolt in the 5.5 ones.

Now out back I am not sure on as I did not mess with that.

But knowing the 2 different patterns have different drum brakes so as a guess besides swapping axle shafts you would need to swap the backing plates because of the wider shoes.

Now could the backing plates be the same but the axle shafts be longer from the bearings out to the wheel mounting?

Maybe someone can look up the backing plates for a 81 F100 with a 9" axle to see if there are different part numbers for them?

In short as was said it might be best to get a parts truck with the right wheel pattern and swap the suspension into your truck and your small pattern into the parts truck and sell it.

Note on the rear axle assy. the gear ratios maybe different as they were between my two trucks.

Oh on the brakes, even that the calipers are different I found the piston dia. was the same so no need to change the master.

And I think the rear wheel cly. were the same between the 2 different brake sizes.

I had to do this check because I was swapping in the power booster & master from my parts truck but had to use all the non-power / 5.5 wheel brake parts with it.

I hope that is the information you were looking for and if you have any questions post it up and I will try and answer them.

Dave ----

[Gary Lewis]

Ok at home on the PC.

From what I found between the 2 81 F100 trucks I had, 1 of each size.

You can not swap the rotors & calipers as the spindles & backing plates are different.

And if you are thinking of swapping the spindles to your truck that will not work either as the kingpins are different sizes.

This was all found when I bolted in the 4.5 beams as the assy. was in good working order but I did not have 4.5 wheel to fit so I tried to swap the rotors from the 5.5 to the 4.5 spindles and found no go

I had to rebuild my 5.5 assy.

So the easy way is to get the beams all the way out to the wheels.

Basic unbolt the beams and bolt in the 5.5 ones.

Now out back I am not sure on as I did not mess with that.

But knowing the 2 different patterns have different drum brakes so as a guess besides swapping axle shafts you would need to swap the backing plates because of the wider shoes.

Now could the backing plates be the same but the axle shafts be longer from the bearings out to the wheel mounting?

Maybe someone can look up the backing plates for a 81 F100 with a 9" axle to see if there are different part numbers for them?

In short as was said it might be best to get a parts truck with the right wheel pattern and swap the suspension into your truck and your small pattern into the parts truck and sell it.

Note on the rear axle assy. the gear ratios maybe different as they were between my two trucks.

Oh on the brakes, even that the calipers are different I found the piston dia. was the same so no need to change the master.

And I think the rear wheel cly. were the same between the 2 different brake sizes.

I had to do this check because I was swapping in the power booster & master from my parts truck but had to use all the non-power / 5.5 wheel brake parts with it.

I hope that is the information you were looking for and if you have any questions post it up and I will try and answer them.

Dave ----

Thanks, Dave. Very good info.

[Socnarftrucks]

Ok at home on the PC.

From what I found between the 2 81 F100 trucks I had, 1 of each size.

You can not swap the rotors & calipers as the spindles & backing plates are different.

And if you are thinking of swapping the spindles to your truck that will not work either as the kingpins are different sizes.

This was all found when I bolted in the 4.5 beams as the assy. was in good working order but I did not have 4.5 wheel to fit so I tried to swap the rotors from the 5.5 to the 4.5 spindles and found no go

I had to rebuild my 5.5 assy.

So the easy way is to get the beams all the way out to the wheels.

Basic unbolt the beams and bolt in the 5.5 ones.

Now out back I am not sure on as I did not mess with that.

But knowing the 2 different patterns have different drum brakes so as a guess besides swapping axle shafts you would need to swap the backing plates because of the wider shoes.

Now could the backing plates be the same but the axle shafts be longer from the bearings out to the wheel mounting?

Maybe someone can look up the backing plates for a 81 F100 with a 9" axle to see if there are different part numbers for them?

In short as was said it might be best to get a parts truck with the right wheel pattern and swap the suspension into your truck and your small pattern into the parts truck and sell it.

Note on the rear axle assy. the gear ratios maybe different as they were between my two trucks.

Oh on the brakes, even that the calipers are different I found the piston dia. was the same so no need to change the master.

And I think the rear wheel cly. were the same between the 2 different brake sizes.

I had to do this check because I was swapping in the power booster & master from my parts truck but had to use all the non-power / 5.5 wheel brake parts with it.

I hope that is the information you were looking for and if you have any questions post it up and I will try and answer them.

Dave ----

This is exactly what I needed. Someone also suggested that the donor truck could be up to a 96. Much appreciated.

[FuzzFace2]

This is exactly what I needed. Someone also suggested that the donor truck could be up to a 96. Much appreciated.

Happy to help when I can as I have gotten so much help from here

I have also heard the later brakes (front) are better but I cant say for sure.

I am pretty sure anything that has ball joints up front, F150 at that point in time, also had the 5.5 pattern as the 4.5 started / stopped with the F100 80-82 trucks.

The earlier F100 trucks I am sure had the 5.5 pattern but their suspension parts will not fit our trucks.

Crazy thinking here but wonder 2 things?

Could have your hubs & rear axles / drums re-drilled for the 5.5 pattern but if you need to replace the rotors or drums would need to have them drilled.

I dont know if they make adapters to go from the 4.5 to the 5.5 size?

It would kick the wheels out maybe 1 inch or more so would need to change the wheel off set to fit the wheels on the truck.

Where were you looking for the 4.5 wagon wheels in what size (w x d)?

Dave ----

[rcarlisle]

I would look for a wagon wheel in the 4.5 size. Aftermarket should have that somewhere?

https://www.summitracing.com/parts/CRR-3105712?seid=srese1&gclid=Cj0KCQjwssyJBhDXARIsAK98ITQrmP1LhLYroaVF26okik4azu5DEq6peP2jUMbxN5qzNFyS8EVXTNkaAs29EALw_wcB

[Socnarftrucks]

I would look for a wagon wheel in the 4.5 size. Aftermarket should have that somewhere?

https://www.summitracing.com/parts/CRR-3105712?seid=srese1&gclid=Cj0KCQjwssyJBhDXARIsAK98ITQrmP1LhLYroaVF26okik4azu5DEq6peP2jUMbxN5qzNFyS8EVXTNkaAs29EALw_wcB

Much appreciated